Uridylation and adenylation of RNAs.

The posttranscriptional addition of nontemplated nucleotides to the 3' ends of RNA molecules can have a significant impact on their stability and biological function. It has been recently discovered that nontemplated addition of uridine or adenosine to the 3' ends of RNAs occurs in different organisms ranging from algae to humans, and on different kinds of RNAs, such as histone mRNAs, mRNA fragments, U6 snRNA, mature small RNAs and their precursors etc. These modifications may lead to different outcomes, such as increasing RNA decay, promoting or inhibiting RNA processing, or changing RNA activity. Growing pieces of evidence have revealed that such modifications can be RNA sequence-specific and subjected to temporal or spatial regulation in development. RNA tailing and its outcomes have been associated with human diseases such as cancer. Here, we review recent developments in RNA uridylation and adenylation and discuss the future prospects in this research area

Role-Play Simulations and System Dynamics for Sustainability Solutions around Dams in New England

Research has shown that much of the science produced does not make its way to the decision-making table. This leads to a gap between scientific and societal progress, which is problematic. This study tests a novel science-based negotiation simulation that integrates role-play simulations (RPSs) with a system dynamic model (SDM). In RPSs, stakeholders engage in a mock decision-making process (reflecting real-life institutional arrangements and scientific knowledge) for a set period. By playing an assigned role (different from the participant’s real-life role), participants have a safe space to learn about each other’s perspectives, develop shared understanding about a complex issue, and collaborate on solving that issue. System Dynamic Models (SDMs) are visual tools used to simulate the interactions and feedback with a complex system. We test the integration of the two approaches toward problem-solving with real stakeholders in New Hampshire and Rhode Island via a series of two consecutive workshops in each state. The workshops are intended to engage representatives from diverse groups who are interested in dam related issues to foster dialogue, learning, and creativity. Participants will discuss a hypothetical (yet realistic) dam-decision scenario to consider scientific information and explore dam management options that meet one another\u27s interests. In the first workshop participants will contribute to the design of the fictionalized dam decision scenario and the SDM, for which we have presented drafts based on a literature review, stakeholder interviews, and expert knowledge. In the second workshop, participants will assume another representative\u27s role and discuss dam management options for the fictionalized scenario. We will report results related to the effectiveness to which this new knowledge production process leads to more innovative and collaborative decision-making around New England dams

Graphene functionalization and its application to polymer composite materials

The progress of graphene research is growing very fast after the discovery of graphene in 2004. This is no doubt that commercialization of graphene will center in the future of graphene. The key challenge is the scale-up production of graphene or graphene-based materials. The hope has been lightened by several breakthrough results introduced above. However, the reproducibility is still concerned, as it is difficult to control the uniformity of individual graphene sheets from “top down” method. It also may be affected by the irregular edge of graphene and randomly dispersed functionalities on graphene sheets. The state-of-the-art techniques are also needed to achieve well-controlled microstructure of functionalized graphene and its derivatives. The article reviewed graphene functionalization and its application to polymer composite materials

Theoretical analysis of direct CPCP violation and differential decay width in D±→π±π+π−D^\pm\to \pi^\pm \pi^+\pi^- in phase space around the resonances ρ0(770)\rho^0(770) and f0(500)f_0(500)

We perform a theoretical study on direct $CP$ violation in $D^\pm\to \pi^\pm \pi^+\pi^-$ in phase space around the intermediate states $\rho^0(770)$ and $f_0(500)$. The possible interference between the amplitudes corresponding to the two resonances is taken into account, and the relative strong phase of the two amplitudes is treated as a free parameter. Our analysis shows that by properly chosen the strong phase, both the $CP$ violation strength and differential decay width accommodate to the experimental results.Comment: 15 pages, 5 figure

A new proof of some polynomial inequalities related to pseudo-splines

AbstractPseudo-splines of type I were introduced in [I. Daubechies, B. Han, A. Ron, Z. Shen, Framelets: MRA-based constructions of wavelet frames, Appl. Comput. Harmon. Anal. 14 (2003) 1–46] and [Selenick, Smooth wavelet tight frames with zero moments, Appl. Comput. Harmon. Anal. 10 (2000) 163–181] and type II were introduced in [B. Dong, Z. Shen, Pseudo-splines, wavelets and framelets, Appl. Comput. Harmon. Anal. 22 (2007) 78–104]. Both types of pseudo-splines provide a rich family of refinable functions with B-splines, interpolatory refinable functions and refinable functions with orthonormal shifts as special examples. In [B. Dong, Z. Shen, Pseudo-splines, wavelets and framelets, Appl. Comput. Harmon. Anal. 22 (2007) 78–104], Dong and Shen gave a regularity analysis of pseudo-splines of both types. The key to regularity analysis is Proposition 3.2 in [B. Dong, Z. Shen, Pseudo-splines, wavelets and framelets, Appl. Comput. Harmon. Anal. 22 (2007) 78–104], which also appeared in [A. Cohen, J.P. Conze, Régularité des bases d'ondelettes et mesures ergodiques, Rev. Mat. Iberoamericana 8 (1992) 351–365] and [I. Daubechies, Ten Lectures on Wavelets, CBMS-NSF Series in Applied Mathematics, SIAM, Philadelphia, 1992] for the case l=N−1. In this note, we will give a new insight into this proposition

Effect of polyhedral oligomeric silsesquioxane nanoparticles on thermal decomposition of cyanate ester resin

A series of cyanate ester resin (CY)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites were prepared successfully. Morphology and thermal stability of the CY and its nanocomposites with POSS were studied by means of scanning electron microscopy (SEM) and Thermogravimetric Analysis (TGA). With the addition of POSS, the thermal stability of CY is dramatically improved. Under air atmosphere, the full decomposition temperature increased by 146 °C, with incorporation of only 1 wt% POSS. The heat generated by the thermal degradation of the CY/POSS nanocomposites is around 4 times less than that of the neat CY. Under nitrogen atmosphere, the char yield of the CY increased up to 15 wt% with addition of the POSS. Besides, the heat required for the degradation of the CY/POSS nanocomposites was much higher than that of the neat CY. These results reveal that the incorporation of the POSS resulted in change of the degradation mechanism of CY. The breakdown of POSS/CY network retarded the breakdown of the triazine rings of CY hence the thermal stability of POSS/CY nanocomposites were improved comparing to that of pristine CY. Furthermore, the formation of char retarded the degradation of benzene rings as well

Toughening of polymers by graphene

Graphene has been regarded as the next-generation carbon nanofiller for polymer nanocomposites. Owing to its superior physical properties, it produces a dramatic improvement in properties of polymers at very low filler loadings. In the past few years, toughening of polymers by graphene has been studied intensively. This article reviews the typical preparation methods of graphene and graphene/polymer nanocomposites. The authors summarize the enhancement effect, optimal filler loading and toughening mechanism for the polymer composites. Effects of some important factors including graphene content, thickness, sheet size, state and interfacial bonding with polymer chains have been addressed. Accordingly, the current challenges and future perspectives for the toughening of polymers by graphene are indicated

Ultra-high enhancement in the toughness of polyethylene by exfoliated natural clay nanosheets

The full exfoliation of inorganic natural clay was engineered in a nonpolar polyethylene following a novel method without the involvement of any chemical modification to the surface of silicate layers. Tensile results showed that the toughening effect was dependent of strain rates, and the toughness of polyethylene was substantially improved by nearly five times with 0.5 wt % natural clay nanosheets at a strain rate of 0.15 s−1. Toughening mechanism was also discussed based on this new exfoliated syste

A computer simulation of stress transfer in carbon nanotube/polymer nanocomposites

The reinforcing efficiency or stress transfer of carbon nanotubes (CNT) on polymers in polymer/CNT composites mainly is controlled by the polymer-CNT interface. Enhancement of polymer-CNT interactions and interfacial crystallisation is as an important way for improvement of the reinforcement experimentally. However, it is not clear about the crystallisation and orientation of polymer chains on the CNT surface, and how the interfacial crystallisation layer affects the failure of the composite. In this work, poly(vinyl alcohol)/CNT nanocomposites was selected as an example and based on the molecular dynamics simulation, the crystallisation process, failure behaviour and stress transfer in poly(vinyl alcohol)/CNT nanocomposites were analysed. The crystallisation temperature of the polymer chains on the CNT surface is slightly higher than the bulk crystallisation temperature. CNT induced crystallisation can be divided into three stages: chain folding, orientating and growing on the CNT surface. A slower crack growth was observed in the interfacial crystallised polymer/CNT systems, compare to relative amorphous systems. The effect of the interfacial crystalline layer on stress transfer is similar as enhanced polymer-CNT interaction systems. The change of the polymer-CNT surficial energy to strain has been used to analyse the interfacial failure and the stress transfer